How popular are IMDB's mobile apps, which allow users to look up information about movies, TV shows, actors, and celebrities? Apparently, very. IMDB bragged this week that its iOS and Android apps have both been downloaded more than 20 million times, for a total of more than 40 million downloads. The apps are free. IMDB announced the numbers this week, as part of a new release of the apps featuring mobile-optimized message boards and check-ins for the apps.